An electric vehicle (EV) and a hybrid vehicle (HV) are silent because of its structure, and therefore it is difficult for pedestrians to be aware of the approach of such a silent vehicle. In recent years, there has been an increased number of electric or hybrid vehicles equipped with a vehicle approach warning apparatus. As disclosed in, for example, JP-A-2004-136831, the vehicle approach warning apparatus generates warning sound, such as pseudo engine sound or pseudo motor sound, to warn pedestrians of the approach of the vehicle.
In the vehicle approach warning apparatus, when a failure occurs in a speaker so that the speaker cannot emit the warning sound, the vehicle approach warning apparatus loses the function to warn pedestrians of the approach of the vehicle. In this case, if a driver continues to drive the vehicle without being aware of the failure in the speaker, the vehicle approach warning apparatus is more of a danger than a protection for pedestrians. A reason for this is that although the driver drives the vehicle on the assumption that the warning sound is emitted to the pedestrian, no warning sound is emitted in reality. Therefore, it is important to detect a failure in the vehicle approach warning apparatus.